By Steve Schow — March 13, 2017
Estimations of emerging infectious diseases between 1940 and 2004, suggest 335 such entities appeared in that period, or about five emerging infectious disease events per year. NOTE: There are three categories of infectious diseases: 1) established infectious diseases like TB, malaria, and tapeworms; 2) newly emerging infectious diseases like SARS, MERS, new influenza subtypes, Nipah, Lyme disease, and HIV; and 3) re-emerging diseases like West Nile virus in the Americas, MRSA, XDR-TB and vancomycin-resistant enterococci.
New human pathogens must come from somewhere. Unsurprisingly, most arise from animals. Around 72% of current human infectious diseases, even those exclusively in humans like measles, pertussis, mumps and hepatitis B, are of zoonotic origin, probably coming from wild animals.
Microbes that normally colonize animals spill over into humans once they acquire the attributes that allow them to do so. Darwinian evolution drives the adaption and survival optimization of the microbe for human hosts. The infectious organisms may become so finely tuned to humans that they become exclusive pathogens of humans. Classic cases of opportunistic spillover from animals to humans include HIV (primates), monkeypox and Ebola (primates); SARS and MERS (civet cats and bats); human Q-fever (dairy goats) and influenza (waterfowl and swine)........To Read More....